An inverter-integrated electric compressor has an inverter accommodating section (inverter box) integrated with the periphery of a housing, which accommodates an electric motor and a compressing mechanism. The inverter accommodating section accommodates an inverter device that converts DC power received from a power supply, such as a generator or a battery, into three-phase AC power and supplies it to the electric motor. The inverter device includes high-voltage components, such as a head capacitor or an inductor; a power board provided with a plurality of semiconductor power switching devices and a power-system controlling circuit that operates the semiconductor power switching devices; a CPU board on which is mounted a circuit having devices that operate at low voltage, such as a CPU; and a bus-bar assembly which includes a plurality of integrated bus bars, constituting the electrical wiring inside the inverter device, and which is composed of insert-molded insulating resin material.
Since such an inverter-integrated electric compressor is mounted and used inside an engine compartment of a vehicle, it is used in an environment having a temperature change from a low temperature of several tens of degrees Celsius below zero to a high temperature of a several tens of degrees Celsius above 100° C. Therefore, in order to guarantee operation by protecting the various types of electrical equipments (electrical components and electronic components) constituting the inverter device from the surrounding environment, heat protection and water drop protection against condensation are required in addition to vibration protection.
Accordingly, it has been proposed to enclose a gel material or a resin material, such as silicone gel, inside the inverter accommodating section (inverter box) accommodating the inverter device up to at least a level where the electrical equipments are covered (for example, refer to Patent Documents 1 and 2).